[Intel-gfx] [PATCH 5/7] dyndbg: fix readback value on LEVEL_NAMES interfaces

Jim Cromie
2022-11-11T22:17:59Z

Since sysfs knobs should generally read-back what was just written
(unless theres a good reason to do otherwise), this result (using
test_dynamic_debug.ko) is suboptimal:

echo L3 > p_level_names
cat p_level_names
4

Fix this with a -1 offset in LEVEL_NAMES readback.

NOTE:

Calling this a BUG is debatable, and the above is slightly inaccurate
wrt "read-back"; whats written is a LEVEL_NAME (a string). Whats read
back is an integer, giving the 'edge' of the 'low-pass-filter'

The actual test looks like:

RTT: L4 -> p_level_names : 4 :: DOING: levels 4-1
[ 17.509594] dyndbg: "L4" > p_level_names:0x4
[ 17.510115] dyndbg: apply: 0x1f to: 0xf
[ 17.510506] dyndbg: query 0: "class L4 +p" mod:*
[ 17.510992] dyndbg: split into words: "class" "L4" "+p"
[ 17.511521] dyndbg: op='+'
[ 17.511811] dyndbg: flags=0x1
[ 17.512127] dyndbg: *flagsp=0x1 *maskp=0xffffffff
[ 17.512604] dyndbg: parsed: func="" file="" module="" format="" lineno=0-0 class=L4
[ 17.513414] dyndbg: applied: func="" file="" module="" format="" lineno=0-0 class=L4
[ 17.514204] dyndbg: processed 1 queries, with 1 matches, 0 errs
[ 17.514809] dyndbg: bit_4: 1 matches on class: L4 -> 0x1f
[ 17.515355] dyndbg: p_level_names: changed bit-4: "L4" f->1f
[ 17.515933] dyndbg: total matches: 1
crap [[ 5 != 4 ]]

This -1 adjustment just reports the edge consistently with its
input-mapping.

Fixes: b9400852c080 (dyndbg: add drm.debug style (drm/parameters/debug) bitmap support)

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
lib/dynamic_debug.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 009f2ead09c1..48ca1387a409 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -794,6 +794,8 @@ int param_get_dyndbg_classes(char *buffer, const struct kernel_param *kp)
return scnprintf(buffer, PAGE_SIZE, "0x%lx\n", *dcp->bits);

case DD_CLASS_TYPE_LEVEL_NAMES:
+ return scnprintf(buffer, PAGE_SIZE, "%d\n", *dcp->lvl - 1);
+
case DD_CLASS_TYPE_LEVEL_NUM:
return scnprintf(buffer, PAGE_SIZE, "%d\n", *dcp->lvl);
default:
--
2.38.1